Abstract: A blur filter for use with a multi-element electro-optical sensor is formed with a plurality of diffractive elements positioned adjacent each other with each of the elements being comprised of uniformly spaced concentric diffractive features. The plurality of diffractive elements are secured in a plane near the sensing surfaces of a multi-element electro-optical sensor. Each element of the multi-element sensor has a plurality of sensing surfaces for receiving incident light from a plurality of diffractive features.

Abstract: A method for forming an optical grating within a waveguide integrated on a substrate includes the step of depositing on a substrate successive layers of material constituting a waveguide such that the waveguide has a periodically varying width along a portion of its longitudinal axis. The deposition may be accomplished by depositing by selective area epitaxy at least some of the successive layers through a mask having a periodically varying width along at least one edge. The successive layers deposited through the mask may constitute a plurality of quantum well layers separated from each other by barrier layers which collectively form a multiple quantum well stack.

Abstract: A method for forming a grating in a photosensitive medium such as a photosensitive optical fiber. The method comprises impinging a pair of interfering, actinic beams onto the medium, and during the impinging step, advancing the illuminated portion of the interference pattern relative to the medium. The advancement is carried out without changing the phase, or registration, of the interference pattern. According to one embodiment of the invention, a grating having a spatially dependent period is produced by varying the wavelength or the intersection angle of the actinic beams during the advancement. According to a second embodiment of the invention, a grating having a spatially dependent refractive index perturbation is produced by varying the dose of actinic radiation received by the medium during the advancement.

Abstract: A multi-beam generating element generates an even number of multiple beams having a uniform light intensity. The multi-beam generating element has a grating constructed by repeatedly arranging basic phase patterns, wherein the basic patterns are composed of at least two kinds of rectangular patterns having non-uniform widths and different phase heights. The basic phase patterns are fabricated by superposing rectangular patterns having non-uniform widths and single phase heights to form a multi-layer arrangement. In an optical printing apparatus having the grating, the multiple beams coming out of a multi-beam generating element are applied to a multi-channel acousto-optical element, a Dove prism rotating the angle of the aligned direction of the multiple beams having light intensities which have been modulated, and then the beams are scanned with a rotating polygonal mirror.

Abstract: The present invention relates to a method and a device for transmitting images via a transmitting medium, for example, optical fibers, without digitizing images (hereafter called "direct image transmission") and, more particularly, a method and a device for direct image transmission by spectral coding. It is an object of the present invention to provide a method and a device for all optical types of direct image transmission that permits two-dimensional images to be directly transmitted without electrical driving units for scanning or tuning images by distributing light from a point source spectrally so that each pixel in the resulting two-dimensional image corresponds one-to-one with the light having a specific wavelength.

Abstract: The optical system of the invention includes a phase type Fresnel zone plate 5. The zone plate 5 includes thereon a central zone C located around the optical axis, through which light flux 2 emanating from an object and having a relatively small divergence angle passes, and a peripheral zone P located on the outside thereof. The central and peripheral zones C and P have given Fresnel pitches and blazing angles, so that the peripheral zone P can make use of diffraction higher in order than that used by the central zone C to obtain the desired refractive power. Although the minimum pitch of the phase type Fresnel plate zone is thus relatively larger in the peripheral zone P, the optical system is not only satisfactory in terms of the effect on correction of chromatic aberration and refractive power but ensures a good image surface contrast as well.

Abstract: A display device comprises a liquid crystal spatial light modulator (1) associated with diffractive means, such as a diffraction grating comprising grating elements (5). The diffraction grating is illuminated by a light source (6, 7) and each element is chirped and blazed so as to separate the primary colors of the illuminating light and direct them to individual light-modulating elements (R, G, B) of the modulator (1). By dispensing with conventional color filters, the efficiency of the display device is improved. Further, the focusing action of the grating elements (5) directs light to the elements of the modulator (1) so as to prevent light wastage caused by blocking of light by opaque regions of the display.

Abstract: A color separation microlens is fabricated to be a single micro-optical element made up of a color separation grating integrated with a refractive lens. The color separation microlens separates the spectrum into distinct color spots and focuses these spots to a common plane. The spots fall at the locations of the different diffraction orders of the grating. The color separation is done by the grating, and the focusing is done by the lens. The color separation microlens can be fabricated as a monolithically integrated element (an element in which the grating and the lens are combined to a single surface) and can also be fabricated as a dual-sided thin wafer (a wafer in which the grating is on one side and the lens is on the other).

Abstract: A multi-beam generator has a grating that is provided on a substrate and which is composed of at least three rectangular patterns of unequal width each having only two phase levels. The generator has high efficiency of light utilization, produces multiple beams of uniform intensity from a single laser beam and can be fabricated by a simple process.

Abstract: A surface emitting laser diode comprises a circular grating defined on the top surface of the diode for emitting a laser therethrough, an active layer for generating the laser in the region thereof under the circular grating, a reflection layer for preventing the laser from emitting through the bottom surface of the diode and a first contact, which includes a plurality of electrodes, for providing the active layer with carriers of a first conduction type and a second contact for providing the active layer with carriers of a second conduction type.

Abstract: This invention is related to a monochromator which employs a spherical mirror, a traveling plane mirror with simultaneous rotation, and a varied spacing plane grating. The divergent beam from the entrance slit is converged by the spherical mirror located at the various positions in the monochromator depending of the inventive system. To provide the meaningful diffraction efficiencies and to reduce unwanted higher order lights, the deviation angle subtending the incidence and diffraction beams for the plane grating is varied with the position of the traveling plane mirror with simultaneous rotation located in the front or back of the plane grating with wavelength scanning. The outgoing beam from the monochromator goes through the fixed exit slit and has same beam direction regardless of the scanning wavelength.

Abstract: An optical pickup apparatus in which light from a light source is led to an information medium and reflected light from the information medium is led to a hologram to be incident as a +1st order diffraction beam on a photodetector to obtain information signals. The hologram has a stair-like cross-sectional configuration, and a ratio of the width of a step of the stair-like cross-sectional configuration relative to a grating pitch of the hologram is arranged to vary in accordance with a position within a surface of the hologram.

Abstract: A zone plate focusing radiation comprises a plurality of surface portions (20a, 20b, 20c, 20d, 30) corresponding to zones of the zone plate. The surface portions are positioned in a plurality P of parallel planes such that each surface portion diffracts radiation out of phase with respect to adjacent surface portions such that radiation diffracted by the surface portion constructively interferes at a focus of the zone plate. The p.sup.th plane is dielectrically spaced from the first plane by n.lambda., where .lambda. is the wavelength of the radiation and n is an integer.

Abstract: A quantum grid infrared photodetector (QGIP) includes a semiconductor substrate with a quantum well infrared photodetector (QWIP) mounted thereon. The QWIP includes a lower contact layer formed on a planar surface of the substrate and a stack of alternate planar barrier layers and planar well layers sandwiched between the lower contact layer and an upper contact layer. The planes of the barrier layers and well layers are substantially parallel to the plane of the planar surface. A plurality of single-slit diffraction units are arranged as a grid in the stack for diffracting incident infrared radiation into a continuum of radiation components directed toward the well layers at different angles with respect to the planes of the well layers. The diffraction units are composed of cavities that extend through the barrier layers, the well layers and the upper contact layer. The cavities have rectangular, square and round shapes and are arranged in rows and columns to form the grid.

Abstract: A method and apparatus for splitting, scanning and receiving a beam of light is disclosed. Binary optic array components are used to split, in an angular manner, an input beam into multiple beams, traveling in different directions. Miniaturized array element BOCs arranged in "n" different groups are used, wherein n is dependent upon the number of split beams needed or desired. An offset is introduced between the optical axis of each of the corresponding pair of miniaturized BOCs. By varying the offset over time, the resultant beam(s) can be scanned in one, two or three dimensions. Piezo-electric drivers controlled by a processor may be used to move the array in order to vary the offset. The device may also include a collection area to collect the returned scanned beams by using an array of optic components integrated with the scanner. The collected beams are then focused onto detectors.

Abstract: A deflection plate for deflecting laser beams includes a transparent plate on which two grating areas are formed on the same surface. The first grating area has a plurality of parallel grooves. The second grating area has a plurality of grooves in a predetermined pattern. The depth and/or the duty ratio of the grooves in the first grating area differs from that in the second grating area.

Abstract: In a preferred embodiment, a method of producing embossed first and second elongate, edgewise side by side, repeating, optical patterns on a sheet for use in producing secure identification means, the method comprising: continuously embossing the first and second optical patterns on the sheet, such that the first and second patterns repeat at different rates, so that the first pattern will "walk" with respect to the second pattern.

Abstract: An optical pick-up device comprising an optical system including a light source and an optical diffraction grating element and a light receiving element, wherein the optical diffraction grating element guides the 0th-order diffracted lights of a light beam emitted from the light source onto a recording medium and guides the first-order diffracted lights of a reflected light from the recording medium onto the light receiving element to produce a plurality of focused light spots having the same light amount, wherein the optical diffraction grating element includes diffraction gratings having a configuration in which grooves and flat lands each positioned between the adjacent grooves are successively alternately formed, wherein the diffraction gratings have the same groove depth, groove width and groove tilt angle in order to obtain a constant 0th-order diffraction efficiency and first-order diffraction efficiency in the optical diffraction grating element while the pitches of the diffraction gratings are made d

Abstract: A diffraction grating providing an optically variable image includes a pixellated diffraction grating in which each pixel is an individual optical diffraction grating so that the pixellated diffraction grating when illuminated generates an optically variable image. In another aspect the grating in some or all of the pixels of a diffracting grating formed by a regular matrix of pixels is arranged such that a reproduction of the grating by reflection contact printing generates a zero-order pattern which is grossly flawed by Moire or Talbot fringe effects. A method of forming the diffraction grating includes producing a counterpart pixellated diffraction grating of a substantially optically invariable image wherein each pixel of the optically invariable image is maped to a respective pixel of the pixellated diffraction grating.

Abstract: An optical scan device comprising a light source and an optical diffraction grating element movable relatively to the light source, which is designed to substantially linearly scan a recording medium in a predetermined direction with a uniform light amount of a light beam emitted from the light source as the optical diffraction grating element moves relatively to the light source. The optical diffraction grating element comprising diffraction gratings having a configuration in which grooves and flat lands each positioned between the adjacent grooves are successively alternately formed, wherein the diffraction gratings have the same groove depth, groove width and groove tilt angle in order to obtain a constant 0th-order diffraction efficiency and first-order diffraction efficiency in the optical diffraction grating element while the pitches of the diffraction gratings are made different by setting a different land width for each diffraction grating.

Abstract: A segmented article is disclosed which has selected Bragg reflection characteristics for a selected input wavelength. The article includes alternating sections of optical materials which are aligned and have refractive indexes different from adjacent sections to form at least one superperiod consisting of a plurality of segments such that each segment consists of a section of a first optical material and a section of a second optical material. At least one segment of the superperiod is different in optical path from another segment of the superperiod, and the interfaces between sections of the superperiod create backward travelling waves of complex amplitude at the selected input wavelength. The sequentially odd interfaces in the superperiod form a first set of interfaces and the sequentially even interfaces in the superperiod form a second set of interfaces.

Abstract: An aperture device for use in an optical apparatus has a plurality of aperture blades which cooperate in collectively defining an aperture of a desired size. The inner edge of at least one of such blades defining one side of the aperture is uneven over at least part of the length of the inner edge. The spacing between adjacent relatively high portions and relatively low portions, as well as the depth, is smaller than the exposed length of the inner edge of each aperture blade when the aperture device has been operated to the minimum aperture size. Preferably, the spacing between adjacent crests or between adjacent high portions and low portions of the unevenness varies in a non-periodic manner.

Abstract: A chirped distributed Bragg grating optical fibre filter comprises an adiabatically tapered single mode optical fibre provided on the taper with a distributed Bragg grating of uniform pitch.

Abstract: An optical pickup apparatus in which light from a light source is led to an information medium and reflected light from the information medium is led to a hologram to be incident as a +1st order diffraction beam on a photodetector to obtain information signals. The hologram has a stair-like cross-sectional configuration, and a ratio of the width of a step of the stair-like cross-sectional configuration relative to a grating pitch of the hologram is arranged to vary in accordance with a position within a surface of the hologram.

Abstract: A method of fabricating a diffraction grating comprises the steps of illuminating a first hyperbolic diffraction grating having a spatial frequency of f/2 with a spherical wave from a point light source to produce a diffracted ray, diffracting the diffracted ray from the first hyperbolic diffraction grating with second and third hyperbolic diffraction gratings having a spatial frequency of f, merging the diffracted rays from the first and second hyperbolic diffraction gratings on a photographic plate to record interference fringes. The point light source, the first, second and third diffraction gratings, and the photographic plate are disposed to satisfy the relationship ##EQU1## where d is the distance between the point light source and the first diffraction grating and c is the distance between the first diffraction grating and each of the second and third diffraction gratings and also the distance between each of the second and third diffraction gratings and the photographic plate.

Abstract: A method and apparatus for simultaneously exposing an optical fiber 32, made of a material which has a refractive index that can be permanently changed by exposure to light of a predetermined intensity at a predetermined wavelength, to two writing light beams 268,272 which intersect and interfere in a predetermined region 30 of the fiber 32 so as to create an interference pattern along a longitudinal axis of the fiber 32, for a time long enough to form a permanent refractive index variation in the waveguide. Each of said two writing beams have a predetermined number of wavelengths, each wavelength being sufficiently different from each other so as to cause said refractive index variation to be an aperiodic variation. Also, each wavelength represents a Fourier component of the desired aperiodic refractive index variation.

Abstract: The current limits of resolution of multi-element optical systems are exceeded by reducing the number of elements while introducing at the critical aperture a blazed transmission grating having grating rings of low bending power defined by multiple plateaus. By illuminating the optical train with monochromatic light that constitutes a multiplicity of distributed sources having a substantial temporal coherence but spatial incoherence and by varying the slopes and widths of the grating rings, local phase delays are introduced that adjust aberrations in the optical system, providing an aligned composite wavefront. The system and method may be used for presenting an image, as for a wafer stepper, or for viewing an image, as in a microscope.

Abstract: In a method of producing a .lambda./4-shifted diffraction grating, a positive type photoresist is applied to a substrate so that the surface level of the photoresist is in the vicinity of the node of the nodes in a standing wave light intensity distribution in the thickness direction of the photoresist that is nearest to the substrate, the light intensity distribution is produced by interference between incident light in the film and light reflected by the substrate. Then, the photoresist is subjected to two-luminous-flux interference exposure, followed by development, providing a pattern of photoresist films regions each having an over-hanging portion.

Abstract: Designs for cylindrical-wave controlling, generating and guiding devices are disclosed, which include multi-cylindrical-layer reflector and anti-reflection for unguided cylindrical waves, and concentric-circle-grating waveguide reflector, directional coupler and distributed feedback structures for guided cylindrical waves. A multi-cylindrical-layer structure takes the form of cylindrical layers wrapped concentrically around a central rod. A grating waveguide structure takes the form of a slab waveguide in which one of the slabs has circular ridge-groove grating. Layer and ridge-groove spacings are critical to the functionality of these structures. Design rules are outlined. These structures are important components for cylindrical wave controls. Designs of narrow-linewidth and high-power surface-emitting semiconductor lasers using the grating reflectors and 90-degree couplers are also disclosed.

Abstract: A method of fabricating diffraction gratings wherein a photomask is arranged on a substrate which is coated with a photoresist, light is to be incident thereupon at an acute angle relative to the normal direction of the photomask, and a bright/dark pattern is formed on said photoresist by the interference of the transmission light that has passed through the photomask and the diffraction light. The invention further deals with a photomask used for the above method.

Abstract: A zero-degree mirror reflection hologram is embedded into a vehicle windshield to reduce veiling glare. The hologram partially reflects sunlight in the visible wavelength range incident on the windshield between 0 and substantially 70 degrees, and therefore blocks a substantial portion of visible sunlight that would otherwise pass through the windshield and reflect off the dashboard. The portion of light that does reflect off the dashboard which could enter the driver's eyebox does not reflect appreciably off the hologram because the hologram reflection peak is in the ultraviolet at high off-axis angles.

Abstract: An optical waveguide device comprises an optical waveguide for guiding an optical wave therethrough, and a grating coupler located on a surface of the optical waveguide in order to radiate the guided optical wave, which travels in the optical waveguide, out of the optical waveguide. The grating coupler is provided with a plurality of bars, the heights h of which increase approximately linearly and little by little in the direction along which the guided optical wave travels. The inclination b of the variation of the bar heights h satisfies the condition ##EQU1## where a represents a coefficient which determines a radiation loss coefficient .alpha. (.alpha.=ah.sup.m, where 2<m), and L represents the length of the grating coupler, which length is taken in the direction along which the guided optical wave travels.

Abstract: Disclosed is apparatus for continuous wideband tuning of lasers, along with means for relating such tuning to a reference wavelength, by maintaining any desired offset from that reference wavelength. Also disclosed are multichannel fiber optics communications networks employing the above means, said networks being self organizing in terms of the wavelengths of their channels.

Abstract: A process of producing a diffraction grating comprises the steps of forming a coating layer on a first diffraction grating layer of a resin formed on a substrate without damaging the diffraction grating layer, removing a portion of the coating layer positioned on the first diffraction grating layer by etching to form a second diffraction grating layer of the coating layer having the reverse phase to that of the first diffraction grating layer, removing the first diffraction grating layer, and etching the substrate with a mask of the second diffraction grating layer, so that the diffraction grating having the reverse phase can be easily produced. When the first diffraction grating layer is left and both the first and second diffraction grating layers are used as a mask, the diffraction grating having a period half times as large as that of the first grating layer can be easily produced.

Abstract: Methods for creating a plurality of holographic diffraction grating patterns in a raster scan fashion. In accordance with the method, the desired pattern is made up of a large plurality of individual spots, each spot comprising a holographic diffraction grating of a predetermined grating spacing and angular orientation for that spot. Variation of the angular orientation and/or grating spacing between spots and/or groups of spots provide the desired holographic effect. The spot locations may vary as desired, including locations drawing out a desired pattern, and two-dimensional orthogonal matrices in which a pattern is drawn by variations between spots or group of spots as in a raster scan type image. Various embodiments and methods for creating the same are disclosed.

Abstract: A grating having holographic properties is employed in a pixel clock for a raster-output scanner. A pilot beam, off-axis from the writing beam creating a latent image on the photoreceptor, is focused on the grating. The grating is adapted to direct a portion of the pilot beam to a photodetector in a fixed point location. The holographic properties of the grating ensure that a wave associated with a reflected interference pattern is always directed at the photodetector throughout the scan path of the pilot beam.

Abstract: An optical diffraction grating element comprising diffraction gratings having a configuration in which grooves and flat lands each positioned between the adjacent grooves are successively alternately formed, wherein the diffraction gratings have the same groove depth, groove width and groove tilt angle in order to obtain a constant 0th-order diffraction efficiency and first-order diffraction efficiency in the optical diffraction grating element while the pitches of the diffraction gratings are made different by setting a different land width for each diffraction grating.

Abstract: A diffractive optical element and a method to produce same is disclosed. The optical element comprises a base and at least first and second phase zones wherein the first phase zone comprises a first multiplicity of steps and the second phase zone comprises a second multiplicity of steps and wherein the first multiplicity and the second multiplicity of steps are different. The method to produce the diffractive optical element of the present invention includes the step of defining a collection of masks for creating stepped phase zones wherein at least one of the collection of masks partially masks out at least one phase zone such that the at least one phase zone will be partially etched.

Abstract: An infrared polarizer has a transparent substrate on which a pattern of spaced metal stripes is deposited. The stripe thickness is approximately equal to at least the stripe spacing which results in a substantial increase of the polarization contrast as compared to that of conventional polarizers having thinner stripes.

Abstract: An optical device is disclosed for diffracting an incident beam of radiation to form a plurality of discrete diffracted beams of different orders. The optical device comprises two diffraction gratings which are supported on a substrate and are separated from each other by a thin film. In order to obtain the advantages of a doubly-periodic structure, the thickness of the thin film between the two gratings is very accurately controlled to be on the order of the wavelength of the incident beam of radiation.

Abstract: A grating lens is disclosed in which diffraction efficiency varies in the focusing direction of light on a surface of the lens. Also disclosed is a focusing grating coupler in which the diffraction efficiency of a grating formed on an optical waveguide, which is formed on a substrate, varies in the focusing direction of light.

Abstract: An ophthalmic lens exhibiting diffractive power has a plurality of diffractive zones and smooth surfaces. The zones are arranged such that R.sub.0.sup.2 does not equal R.sub.1.sup.2 -R.sub.0.sup.2 where R.sub.0 is the radius of the central zone and R.sub.1 is the radius of the first annular zone.

Abstract: An optical element having a substrate and a composite grating pattern formed thereon. The pattern is constituted with two different kinds of grating patterns superimposed on the substrate. When one of the two kinds of grating patterns is formed in a Fresnel lens pattern, a light focusing or collimating function (i.e. a lens function) is implemented. When the other pattern is formed in an equally separated linear grating pattern, the optical element develops the lens function and a function to diffract lights through the linear grating. When one of the two kinds of grating patterns is formed in a Fresnel lens pattern and the other pattern is implemented in an unequally separated linear grating pattern, a lens function to focus lights onto a point and a cylindrical lens function to focus lights in a linear contour are obtained. Consequently, when parallel lights are incident to the optical element, there occurs astigmatism.

Abstract: An optical device suitably employable in intraocular and contact lenses that employs a phase zone plate of a Cohen lens design that relies on a small number of zones to provide multifocal images.

Abstract: A multifocal optical device is provided for focusing light traveling parallel to an optical axis of the device. The multifocal optical device comprises a multifocal phase zone plate including at least two annular zones disposed substantially concentrically about the optical axis and spaced in a radial dimension from the optical axis in proportion to the square root of q, where q is an integer zone number; and an absorbing material disposed on a portion of ones of the annular zones for absorbing a portion of the light.

Abstract: A phase diffraction grating apparatus which is usable to generate an array of N spots, where n is an even integer, and the N spots are substantially equally spaced. The generation of an even number of spots is achieved using a translation symmetry in the grating design. Illustratively, the intensities of the N spots are substantially equal. Binary, multi-level, and continuous phase grating embodiments are disclosed. In the case of the multi-level and continuous embodiments, the uniform intensity is obtained using a reflection symmetry in the grating design.

Abstract: An artificial eye lens such as a contact lens or intra-ocular lens corrects astigmatism by two sets of substantially linear parallel zones arranged to diffract light predominantly into one order at one orientation, the spacing of the zones diminishing on either side of the linear axis. In addition circular diffraction zones may be provided to give both spherical and cylindrical power for astigmatism correction.

Abstract: A diffraction grating has incident and emitting side gratings respectively formed on front and rear faces of a diffraction substrate composed of a transparent plane-parallel plate. A pitch .LAMBDA..sub.1 of the incident side grating, a pitch .LAMBDA..sub.2 of the emitting side grating, a refractive index n.sub.1 of the diffraction substrate, a thickness t of the diffraction substrate, and incident angle .theta..sub.1 of light incident to the incident side grating, an angle .theta..sub.2 of diffraction within the diffraction substrate, an emission angle .theta..sub.3 of light emitted from the emitting side grating, a distance T from the emitting side grating to a face for receiving the emitted and diffracted light, and a wavelength .lambda. of the light are set to satisfy the following conditions.

Abstract: A diffraction grating comprises the plurality of grating rings provided at positions such that their radii r are selected so that a function .phi.(r) of r satisfies the following differential equation and initial conditions, ##EQU1## where .lambda. is the wavelength of a scanning light beam, f is the focal length of the diffraction grating, r is the radius from the center of diffraction grating, M is the distance from the diffraction grating to a scanning surface expressed as a multiple of the focal length f, and moreover the relation.phi.(r)=n+.phi.(0)n=0, 1, 2, . . .(n is a non-negative integer)is satisfied.